C: Spinal cord and Spinal nerves Flashcards
What is the functional difference between the dorsal and ventral roots?
Dorsal - carries sensory afferent fibres
Ventral - carries motor efferent fibres
Where do the dorsal and ventral roots unite to form spinal nerves?
In or near the intervertebral foramen
What do the dorsal rami of spinal nerves supply?
Muscles and skin of the back region
What do the ventral rami of spinal nerves supply?
Muscles and skin of the front of the body and the limbs
Name 3 conditions in which the composition of CSF may be altered?
1) Meningitis
2) SAH
3) MS
At what vertebral level does the spinal cord terminate in an adult?
L1
At what vertebral level does the spinal cord terminate in a neonate?
L3 vertebral body
What is the most common site from which CSF is sampled in adults?
Lumbar cistern
What position is the patient in to perform a lumbar puncture?
Positioned on one side, perpendicular to the bed and curled up as much as possible, needle is inserted into the midline between the L3/L4 vertebra
What surface landmarks would you use to determine the point at which to insert the needle in a lumbar puncture?
Spinous processes
Line between 2 iliac crests
Why is the patient asked to curl up when taking a CSF sample?
Flex the vertebral column - spinous processes are more prominent for obtaining correct site
Intervertebral space is made larger
Starting with the skin which layers are pierced by a lumbar puncture needle?
1) Skin
2) Subcutaneous tissue
3) Supraspinous ligament
4) Interspinous ligament
5) Ligamentum flavum
6) Epidural space
7) Dura
8) Arachnoid
9) Subarachnoid space
In what way is bladder function affected by compression of the cauda equine eg. by a tumour?
Difficulty with micturition
In a series of cross-sections taken from each region of the spinal cord, which section would contain the most white matter why?
Cervical - closest to the head, conveying more axons than any other region
In which region of the spinal column is the dorsal white matter subdivided into 2 columns on each side?
Thoracic (above T6) and cervical
What kind of info is carried in the cuneate and gracile fascicles?
Both discriminative touch, vibration and proprioception
Gracile - below T6
Cuneate - above T6
In which spinal cord segments is the ventral grey horn enlarged due to the accumulation of motor neurons for innervation of the limbs?
Cervical (upper limb)
Lumbar (lower limbs)
What types of sensory info are carried by the spinothalamic tract?
those essential to survival - pain, temperature, some touch and pressure
Does the spinothalamic tract run ipsilaterally or contralaterally in the cord?
Contralaterally
In which region of the cerebral cortex does the spinothalamic pathway terminate?
Post-central gyrus
Where does the secondary sensory area for somaesthetic information lie?
Superior parietal lobe - posterior to post-central gyrus
What types of sensory info are carried in the dorsal column pathway?
2 point discriminative touch, vibrations and proprioception
Where do the fibres of the dorsal column pathway run at the level of the spinal cord?
Ipsilaterally
Where do the fibres of the dorsal column pathway run at the level of the closed medulla?
Ipsilaterally (cross at the level of the closed medulla)
